Ig.S. Konovalenko, A.I. Dmitriev, A.Yu. Smolin, and S.G. Psakhie / Physical Mesomechanics 15 12 (2012) 8893 88 On the estimation of strength properties of porous ceramic coatings Ig.S. Konovalenko 1 , A.I. Dmitriev 1,2 *, A.Yu. Smolin 1,2 , and S.G. Psakhie 1,2 1 Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634021, Russia   2 Tomsk State University, Tomsk, 634050, Russia A method for estimating the strength properties of a porous ceramic coating was proposed. The method is based on the analysis of preliminary test results on indentation of coatings with defects of varying size and depth of occurrence. The strength properties of the coating were studied by computer simulation combining the discrete description (the movable cellular automata method) and continuous description (the finite difference method). Relationships were found between the parameters of a pore such as its length and depth of occurrence in the coating and the critical stress corresponding to fracture of the coating. The proposed method can be used to study the strength properties of material surface layers and to predict the critical stress in a contact region. Keywords: numerical simulation, movable cellular automata method, porous ceramic coating, strength properties of coatings DOI: 10.1134/S1029959912010092 * Corresponding author Prof. Andrew I. Dmitriev, e-mail: dmitr@ispms.tsc.ru 1. Introduction Today, rapt attention is focused on the issues that con- cern the coating deposition and modification of surface lay- ers of materials for improving their performance [15]. This is especially urgent for various problems of contact inter- action such as friction and wear, in which the interaction between surface layers governs the behavior of a unit or the whole mechanism. The most widespread methods of coat- ing deposition, including wear resistant coatings, are thermo- chemical (thermodiffusion saturation of the surface) as well as chemical and physical deposition methods [15]. The above techniques provide a good combination of necessary physical and mechanical properties of friction surfaces (wear resistance, strength, microhardness, crack resistance, etc.) and saving on alloy additions, which enables the proper modification of the structure and properties of the substrate material. At the same time, friction units under actual oper- ating conditions are exposed to a great number of influ- ences. Cycle operation, high contact stresses and tempera- tures, a variety of active physical and chemical processes change the structure of wear resistant coatings and possibly cause the generation of various defects in them such as mi- cro- and nanopores, cracks, etc. These factors can signifi- cantly change the performance characteristics of the coated materials, even to the point of their failure. In this connec- tion there arises a need to check the quality of coatings not only in the course of friction unit operation but also imme- diately after the surface layer deposition or modification. In recent years, along with the conventional quality con- trol methods for surface layers, new approaches on the ba- sis of nondestructive testing are being developed [68]. An important tool for the development of new quality control methods for surfaces and coatings is computer simulation. It makes possible to analyze the influence of various pa- rameters (physical and mechanical parameters of the sys- tem, loading conditions, etc.) on the mechanical behavior of the coated material under loading. In the present paper a theoretical study is carried out with computer simulation methods to investigate whether it is in principle possible to determine the form of the func- tional dependence of the strength properties of a coating with structural defects such as pores on the depth of their occurrence and characteristic sizes. The calculations are performed in the framework of a combined discrete-con- tinuous approach that has proved to be very effective for the solution of this kind of problems [911]. The process of combining the discrete (the movable cellular automata method) and continuous (the finite difference method) ap- proaches as well as each of the used methods is described in papers [1214]. © Pleiades Publishing, Ltd., 2012. Original Russian Text © Ig.S. Konovalenko, A.I. Dmitriev, A.Yu. Smolin, S.G. Psakhie, 2011, published in Fiz. Mezomekh., 2011, Vol. 14, No. 2, pp. 3945. Distributed worldwide by Springer.